There are very few books that cannot be read
by young people. They may not understand the nuances or the
subtext but, then again, some adults don't either. However, parents
often ask for a list of titles that they can use for their kids.
Here is a starting point.

These books occupy a special place in SF and fantasy. Their target market is
boys 10 to 17 years old. Often referred to as the Hardy
Boys of Fantasy, the book have simple, straight-forward plots, serial by
design. We suggest starting off young readers
with the Dragonlance Chronicles by Margaret Weis and Tracey
Hickman (3 books) or the Dark Elf Trilogy by R.A. Salvatore
(3 books).